/*
silverPDF is sponsored by Aleyant Systems (http://www.aleyant.com)

silverPDF is based on PdfSharp (http://www.pdfsharp.net) and iTextSharp (http://itextsharp.sourceforge.net)

Developers: Ai_boy (aka Oleksii Okhrymenko)

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above information and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR SPONSORS
BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

*/
#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//
// Copyright (c) 2005-2008 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using System.Collections;
using System.Globalization;
using System.Text;
using System.IO;
using PdfSharp.Drawing;
using PdfSharp.Internal;
using PdfSharp.Fonts.TrueType;
using System.Collections.Generic;

namespace PdfSharp.Pdf.Advanced
{
  /// <summary>
  /// Contains all external PDF files from which PdfFormXObjects are imported into the current document.
  /// </summary>
  internal sealed class PdfFormXObjectTable : PdfResourceTable
  {
    // The name PdfFormXObjectTable is technically not correct, because in contrast to PdfFontTable
    // or PdfImageTable this class holds no PdfFormXObject objects. Actually it holds instances of
    // the class ImportedObjectTable, one for each external document. The PdfFormXObject instances
    // are not cached, because they hold a transformation matrix that make them unique. If the user
    // wants to use a particual page of a PdfFormXObject more than once, he must reuse the object
    // before he changes the PageNumber or the transformation matrix. In other words this class
    // caches the indirect objects of an external form, not the form itself.

    /// <summary>
    /// Initializes a new instance of this class, which is a singleton for each document.
    /// </summary>
    public PdfFormXObjectTable(PdfDocument document)
      : base(document)
    {
    }

    /// <summary>
    /// Gets a PdfFormXObject from an XPdfForm. Because the returned objects must be unique, always
    /// a new instance of PdfFormXObject is created if none exists for the specifed form. 
    /// </summary>
    public PdfFormXObject GetForm(XForm form)
    {
      // If the form already has a PdfFormXObject, return it.
      if (form.pdfForm != null)
      {
        Debug.Assert(form.IsTemplate, "An XPdfForm must not have a PdfFormXObject.");
        if (object.ReferenceEquals(form.pdfForm.Owner, this.owner))
          return form.pdfForm;
        //throw new InvalidOperationException("Because of a current limitation of PDFsharp an XPdfForm object can be used only within one single PdfDocument.");

        // Dispose PdfFromXObject when document has changed
        form.pdfForm = null;
      }

      XPdfForm pdfForm = form as XPdfForm;
      if (pdfForm != null)
      {
        // Is the external PDF file from which is imported already known for the current document?
        Selector selector = new Selector(form);
        PdfImportedObjectTable importedObjectTable = this.forms[selector] as PdfImportedObjectTable;
        if (importedObjectTable == null)
        {
          // No: Get the external document from the form and create ImportedObjectTable.
          PdfDocument doc = pdfForm.ExternalDocument;
          importedObjectTable = new PdfImportedObjectTable(this.owner, doc);
          this.forms[selector] = importedObjectTable;
        }

        PdfFormXObject xObject = importedObjectTable.GetXObject(pdfForm.PageNumber);
        if (xObject == null)
        {
          xObject = new PdfFormXObject(this.owner, importedObjectTable, pdfForm);
          importedObjectTable.SetXObject(pdfForm.PageNumber, xObject);
        }
        return xObject;
      }
      Debug.Assert(form.GetType() == typeof(XForm));
      form.pdfForm = new PdfFormXObject(this.owner, form);
      return form.pdfForm;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="page"></param>
    /// <returns></returns>
    public PdfImportedObjectTable GetImportedObjectTable(PdfPage page)
    {
      // Is the external PDF file from which is imported already known for the current document?
      Selector selector = new Selector(page);
      PdfImportedObjectTable importedObjectTable = this.forms[selector] as PdfImportedObjectTable;
      if (importedObjectTable == null)
      {
        importedObjectTable = new PdfImportedObjectTable(this.owner, page.Owner);
        this.forms[selector] = importedObjectTable;
      }
      return importedObjectTable;
    }

    public void DetachDocument(PdfDocument.DocumentHandle handle)
    {
      if (handle.IsAlive)
      {
        foreach (Selector selector in this.forms.Keys)
        {
          PdfImportedObjectTable table = (PdfImportedObjectTable)this.forms[selector];
          if (table.ExternalDocument != null && table.ExternalDocument.Handle == handle)
          {
            this.forms.Remove(selector);
            break;
          }
        }
      }

      // Clean table
      bool itemRemoved = true;
      while (itemRemoved)
      {
        itemRemoved = false;
        foreach (Selector selector in this.forms.Keys)
        {
          PdfImportedObjectTable table = (PdfImportedObjectTable)this.forms[selector];
          if (table.ExternalDocument == null)
          {
            this.forms.Remove(selector);
            itemRemoved = true;
            break;
          }
        }
      }
    }

    /// <summary>
    /// Map from FormSelector to ImportedObjectTable.
    /// </summary>
    Hastable forms = new Hastable();

    /// <summary>
    /// A collection of information that uniquely idendifies a particular ImportedObjectTable.
    /// </summary>
    public class Selector
    {
      /// <summary>
      /// Initializes a new instance of FormSelector from an XPdfForm.
      /// </summary>
      public Selector(XForm form)
      {
        // HACK: just use full path to identify
        this.path = form.path.ToLower(CultureInfo.InvariantCulture);
      }

      /// <summary>
      /// Initializes a new instance of FormSelector from a PdfPage.
      /// </summary>
      public Selector(PdfPage page)
      {
        PdfDocument owner = page.Owner;
        //string path = owner.FullPath;
        //if (path.Length == 0)
        path = "*" + owner.Guid.ToString("B");

        this.path = path.ToLower(CultureInfo.InvariantCulture);
      }

      public string Path
      {
        get { return this.path; }
        set { this.path = value; }
      }
      string path;

      public override bool Equals(object obj)
      {
        Selector selector = obj as Selector;
        if (obj == null)
          return false;
        return this.path == selector.path; ;
      }

      public override int GetHashCode()
      {
        return this.path.GetHashCode();
      }
    }
  }
}
